TOEFL implacable Definition Impossible to calm down or satisfy; unrelenting. Example "She faced the implacable opposition of her neighbors." Sign in to save TOEFL PDF — $25 ← impious implant → Study tips featuring "implacable" TOEFL Academic Vocabulary: Study by Topic Related words TOEFL brighten GRE abash GRE abate GRE abbreviate GRE abbreviation SAT abdicate GRE abduct SAT abet GRE abhor GRE abide SAT abject TOEFL ablaze